The containment well cellars described and claimed in the above noted patents are becoming increasingly recognized for their environmentally-friendly features, as well as for their advantages in well installation and operation. It is among the objects of the present invention to provide accessorial equipment which will further enhance the advantages of this family of sealed well cellars. It will be understood that the features of this invention may be equally of value when employed with other existing and as-yet-to-be-developed well cellars, or simply to hang casing in application where a well cellar is not being used.
Currently in the industry, casing hangers, both the mandrel and slip types, are used to suspend the weight of a second inner casing on first outer well casing. This may be done before or after the inner well casing is cemented in place. Existing casing hangers are a part of the wellhead assembly. Typically, when weight in the form of the blow-out-preventer (BOP) or wellhead assembly is attached to the inner casing and, thereby, supported by the partially cured cement, this weight, in conjunction with vibrations associated with the drilling operations, will cause shifting of the well casings and cracking of the cement. This breaks containment allowing migration of well fluids into the area around the wellhead, which contaminates the soil and can pollute the riparian ground water.
Unlike existing hanger systems, the casing hanger of the present invention is not part of the well-head assembly. Further, the casing hanger of the present invention may be attached to the floor of one of the well cellars described in the above noted patents distributing the weight of the well casings, any attached equipment, and associated drilling forces, over the area of the floor. This inhibits settling of the inner and outer well casings and ensures the cement remains intact for the life of the well so that migration of well gases leading to contamination of the ground water and soil surrounding the well-head is avoided.
A first aspect of the present invention comprises a well completion system including a) a sealed well cellar embedded in a region surrounding a well site, the sealed well cellar collecting well fluids and preventing the fluids from polluting the region surrounding the well site; b) a surface casing hanger secured to a floor portion of the sealed well cellar, the floor portion having a first area, the casing hanger distributing a weight supported by the casing hanger over said first area; c) a surface casing extending through the surface casing hanger and being secured thereto. In one embodiment, the surface casing hanger is welded to an external portion of the surface casing. Alternatively, the surface casing hanger is threaded onto an upper threaded portion of said surface casing. Preferably, the surface casing hanger is secured to a landing ring which is secured to an upper portion of a conductor pipe through which the surface casing extends. The landing ring may additionally include lock down means to which the hanger is secured preventing the surface casing from being pushed upwardly by buoyancy or hydraulic forces.
In a further aspect of the present invention, a well completion system comprises: a) a landing ring secured to an upper region of a conductor pipe, as by welding; b) a surface casing hanger which engages and is supported by the landing ring; c) a surface casing attached to and supported by the surface casing hanger. The well completion system may further include a sealed well cellar having a floor portion and upwardly extending walls, the floor portion of the sealed well cellar being attached to and supporting a weight of the surface casing hanger as well as a weight of the surface casing which is attached thereto. In one embodiment, the surface casing hanger is welded to an external portion of said surface casing. Alternatively, the surface casing hanger may be threaded onto an upper threaded portion of the surface casing. The landing ring may be equipped with a quick-connect fitting to receive a riser.
A third aspect of the present invention is directed to a method of completing a well comprising the steps of a) installing a conductor pipe; b) install a well cellar having a structural, load-bearing floor portion surrounding the conductor pipe; c) securing the well cellar to the conductor pipe; d) installing a landing ring by securing the landing ring to one of i) the conductor pipe and, ii) the cellar floor. The method may include the additional step of attaching a riser to an upper end of the landing ring using a quick connect profile which readily receives the riser and secures the riser thereto. The method may additionally comprise the steps of i) drilling a surface hole through the riser and ii) installing a surface casing with a surface casing hanger secured to an uppermost section of pipe by landing the surface casing hanger on the landing ring. The invention includes the further step of cementing the surface casing in place by pumping cement through the surface casing with adequate pressure to force the cement down through the surface casing and upwardly around an external surface portion of the surface casing. Finally, the steps of i) draining said riser; ii) removing said riser; and, iii) securing a well-head to the surface casing are performed.
Various other features, advantages, and characteristics of the present invention will become apparent after a reading of the following detailed description.